The introduction of photographic cartridge assemblies such as those used for super 8 motion picture film, single 8, and motion picture film and film disc cartridges, the latter being disclosed in GB No. 2,027,225A, have provided unprecedented ease of camera operation. These advances have enabled the least photographically knowledgeable to reap the benefits of modern photographic technology.
Almost all of the amateur photographs taken utilize color film. Very few black and white snapshots are now recorded. Today's commercial color films (for print and transparency use) rely on the technology of multiple coatings of individual layers of photosensitive color-forming silver halide films. Such traditional color films are composed of at least 5 superimposed different layers. Some constructions contain as many as 18 to 20 layers. The complex manufacturing equipment as well as the unique chemical constituents of these layers can be quite costly. The various combinations of manufacturing conditions and raw material differences can produce great product variability. Quality control and closely monitored manufacturing operations add to the product costs. Such color films require chemical sophistication and narrow tolerances in order to produce acceptable color images.
Color photographic systems which do not require multilayer individual color-forming layers have been used in the past. Some of these require the use of dedicated cameras specially equipped with built in devices to separate and record color images on black and white film. Some of these built-in's include color prisms or mirrors with colored filters. Other techniques require using small individual color elements, ruled onto glass as in a "Finlay" screen in a regular ruled format, or on glass wherein an irregular format such as starch grains or blood cells are dyed and used as miniature filters. Such techniques rely on a reusable glass-containing filter permanently mounted in a camera and a single exposure black and white film mated to it to record the color image. A complicated processing sequence of development, developer arrest, silver oxidation, redevelopment, fixation and intermediate water washes are required before the film is ready to be viewed in black and white. Color rendition can only be accomplished by the re-registration of the black and white recording to the camera color filter screen or replica of the camera color filter and subsequently viewing the composite through a very strong light source. The viewing source has to be intense since the light has to pass through the dense silver image as well as the narrow band dark color filter rulings of the screen.
Techniques have also been employed to photochemically print a regular color ruling on the base side of a photographic light-sensitive black and white film such as that known as "Dufaycolor". Such a product involves the step of image formation or photography to be performed through the thick photographic film base (through the printed ruling and the film base) to the light-sensitive silver halide layer on the opposite side. Although this technique permits the use of a flexible film base and non-dedicated cameras, it still requires the use of special developers to produce the positive silver image. The technique presents the same difficulty its predecessor has in that the film requires an intense light source for viewing because the viewed light passes through the dense silver image as well as the colored filters on the other side of the base. Because the filter layer is an integral part of the flexible support, in rolling or packaging the film for use the colored printed layer comes into contact with the light-sensitive layer and can cause a chemical interference with it.
A modern version of this flexible film ruled color screen black and white film is disclosed in U.S. Pat. No. 4,386,151. It obviates the disadvantages of multi-step wet processing by use of the diffusion transfer technique. The ease of processing however is at the expense of reduced sharpness in the final image since a transferred black and white image does not match the sharpness of an original black and white image. No advantages are obtained in the final viewing of the images since one must again view the image through the silver layer and colored filter.
The use of spatial frequency recording and separation of color images onto black and white films has been described in U.S. Pat. Nos. 3,609,010 and 3,586,434. In these patents a conventional camera utilizing a special retrofitted filter with a colored spatial pattern is used to record color images onto conventional black and white film. Such a technique provides black and white images which are recorded in different spatial configurations. In those cases different azimuth positions encode the color information. The technique does not require the viewing of the resultant image through the same colored spatial pattern in order to be seen. Optical reconstruction is necessary for color viewing.
Within the last few years a photographic cartridge assembly commonly referred to as "disc film" or "disc cartridge" assembly has become commercially available and is described, for example, in U.S. Pat. Nos. 4,194,822 and 4,268,145 and GB No. 2,027,225A. The photographic cartridge assembly includes (1) an opaque casing with an exposure window in its front wall and (2) a film unit (or disc) which can contain black and white or multi-layered colored film rotatably mounted in the casing such that successive film portions can be aligned with the exposure window.